Musashi lives with his older sisters Nanami and Misaki, who often use him to their advantage. Lately he’s been getting closer to his cousins Kazuha and Honoka who live next door. It’s like they’re part of his family, or are they like lovers? Either way, every day is full of happiness. One day, all four girls confessed that they had loved him since they were born and asked him to marry them! Suddenly, the delicate balance has been broken and each girl aimed to claim him as their own.